Tuesday, 11 July 2017

Kölsch obergärig (Deutsch-Pilsener)

Now here’s something I’m dead excited about. A description of Kölsch from relatively early in the style’s life.

Kölsch only seems to have coalesced into a definite, definable style around 1900. In the late 19th century top-fermenting brewers in various part of the Rhineland had started brewing beers which were intended to mimic some of the qualities of the new-fangled Lager beers that were flooding the region. Initially these were lumped together as Rheinisches Bitterbier. They had a few features in common, including heavy hopping and a lengthy lagering. Eventually both Düsseldorf and Cologne developed their own specific styles.

But that’s enough from me. Let’s see what Olberg has to say. This is my paraphrasing of his chapter on Kölsch.

Kölsch is a gold-coloured, thirst-quenching, not too heavy, easily-digestible beer that is the national drink of Cologne.

It is usually brewed using the kettle mash process, or by boiling a thick mash once or twice. Though to save time and fuel mostly a kettle mash is employed, with perhaps one thick mash.

For example, mashing in is at 7 AM at a temperature of 35º C, the mash is left to brew until 7:30 and then the temperature raised slowly to 50º C at 8:30 and 70º C at 9:30. The mash is left at this temperature for saccharification (30 to 40 minutes, make an iodine test.). If full saccharification has occurred, raise it to the mashout temperature of 76º C. The lauter tun must be well warmed up beforehand.

Or after saccharification of the mash, about a third is left in the lauter tun while the other two-thirds is brought to the boil in the kettle and returned to the lauter tun to mash out at 76ºC.
Source: Olberg, Johannes (1927) Kölsch obergärig in Moderne Braumethoden, pp 64-65, A. Hartleben, Wien & Leipzig.

So a fairly simple mashing scheme with optionally a single decoction. Next boiling.

A third of the hops are added as the wort is being run into the copper, another third after one hour of boiling and the last third 40 minutes before turning out the kettle. The boil lasts two hours. Usually a small quantity of the hops, 6 to 8 %, are added to the kettle just before emptying it, when the steam has already disappeared. OG is 11 to 12º Balling.
Source: Olberg, Johannes (1927) Kölsch obergärig in Moderne Braumethoden, pp 64-65, A. Hartleben, Wien & Leipzig.

Interesting that there were three hop additions, plus a very, very late on. It all sound very modern, especially that last, very late one.

Here’s how the fermentation went:

The wort is cooled to 10º C and pitched with 1 litre of yeast per 50 kg of malt. The tun fermentation lasts 5 days. The bier is transferred to lagering vessels just like Lagerbier and from this point on is handled and lagered cold in exactly the same way. The lagering vessels are filled to the top and only loosely bunged. After 5 to 6 weeks the beer, without being bunged, can be filtered and sent out to customers.
Source: Olberg, Johannes (1927) Kölsch obergärig in Moderne Braumethoden, pp 64-65, A. Hartleben, Wien & Leipzig.

That’s a pretty cool fermentation, followed by a fairly classic lagering, except for not being bunged. As they were filtering the beer anyway, they seem to have not bothered with the final stage of lagering where, after the bung has been tightly sealed the beer naturally carbonates and clarifies itself. It sounds to me like they must have been force carbonating the beer after filtration. With the bung open, it wouldn’t carbonate itself.

The hopping rate in the kettle is 65 pounds of Lagerbier hops for 1,050 kilos of grist. In addition, before filling, into a lagering barrel of 65 hl, 12 pounds of hops and the water they have been brewed in are put into the barrel. These hops have been mashed with 75º water in a barrel for 30 minutes. The finer the hops, the better the beer will taste and the better its aroma. These beers are not usually bunged.
Source: Olberg, Johannes (1927) Kölsch obergärig in Moderne Braumethoden, pp 64-65, A. Hartleben, Wien & Leipzig.

That’s a pretty heavy hopping rate for a German beer. It works out to about 10.5 lbs per quarter of malt. For comparison, in 1925 Whitbread PA, at 1047º a very similar gravity to the Kölsch being described, had only 7.5 lbs per quarter.*

I’ve come across this practice of mashing hops in hot water before. I guess it’s a sort of dry hopping. Is 75º C hot enough to isomerise the hops? According to the internet, it isn’t. 79º C seems to be the critical temperature. It’s odd they should use a temperature that’s just slightly too cool. Which has me wondering about the exact purpose of this technique.

That wet hopping is the equivalent of about 5.25 oz. per barrel, which is about the same as and English Best Bitter of the period.

I’m sure modern versions are much more lightly hopped. Unfortunately.

* Whitbread brewing record held at the London Metropolitan Archives, document number LMA/4453/D/01/090.

10 comments:

Anonymous
said...

75°C would probably be enough to pasteurise the hops before it goes into the beer, perhaps since less oxygen would be dissolved in the 'hop tea' it also reduces the oxidation. Maybe it even helps extraction since a lot of the hop compounds are now contained in the water and can provide better mixing (my thoughts coming from that some breweries practice dry hopping with nylon bags attached to lengths of chains in massive cylindroconical fermenters). I wonder if it also stops fobbing, thus allowing the barrels to be filled to the brim without excessive foaming?

"A third of the hops are added as the wort is being run into the copper,"

First wort hopping! Recently I have started to do that to all the German ales and lagers I brew at home. Really adds a nice flavor and gentle bitterness. My current Helles fermenting in my chest freezer was brewed with 4 oz. Hallertau Mittelfruh, all first wort hopped. No other additions.

Ron: Have you ever studies the similarities between Kolsch and American Cream Ale. Cream Ale was American ale brewers answer to lagers. Fermented with top fermenting yeast but also contained corn (maize) in the mashbill, it was then lagered. It was heavily hopped for the time. I believe it contained more alcohol by volume than Kolsch. I am interested to hear any thoughts you may have on the subject.

You can filter carbonated beer, if it is cold enough and the CO2 remains in solution. Are there 1920s sources that suggest German brewers were force carbonating anything? I believe it is still considered rather louche there even today.

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